Stable Acidic Water Oxidation with a Cobalt–Iron–Lead Oxide Catalyst Operating via a Cobalt‐Selective Self‐Healing Mechanism

The instability and expense of anodes for water electrolyzers with acidic electrolytes can be overcome through the implementation of a cobalt‐iron‐lead oxide electrocatalyst, [Co–Fe–Pb]Ox, that is self‐healing in the presence of dissolved metal precursors. However, the latter requirement is pernicious for the membrane and especially the cathode half‐reaction since Pb2+ and Fe3+ precursors poison the state‐of‐the‐art platinum H2 evolving catalyst. To address this, we demonstrate the invariably stable operation of [Co–Fe–Pb]Ox in acidic solutions through a cobalt‐selective self‐healing mechanism without the addition of Pb2+ and Fe3+ and investigate the kinetics of the process. Soft X‐ray absorption spectroscopy reveals that low concentrations of Co2+ in the solution stabilize the catalytically active Co(Fe) sites. The highly promising performance of this system is showcased by steady water electrooxidation at 80±1 °C and 10 mA cm−2, using a flat electrode, at an overpotential of 0.56±0.01 V on a one‐week timescale. The [Co–Fe–Pb]Ox water oxidation anode catalyst facilitates long‐term O2 evolution reaction in acidic electrolytes at elevated temperatures. Through a cobalt‐selective self‐healing mechanism, this catalyst operates in the absence of dissolved Pb2+ and Fe3+ precursors deeming it a prospective anode material for low‐cost water electrolyzer systems.